Mr Dutton, now a backbencher, offered reporters a tortured reasoning that it wasn't Mr Turnbull he wanted to block but Labor's Bill Shorten. It was just Mr Turnbull was in his way.

It was the same reasoning Mr Turnbull gave in an appeal for Liberal unity.

However, Mr Turnbull also argued that economic growth and higher employment were at risk should he be turfed.

Mr Shorten's reply in Parliament was an unsuccessful motion of no-confidence launched with the line: "This government has lost the will to live."

Mr Dutton revealed an implied criticism of Mr Turnbull hidden while he was a minister: "I will make sure that I can do all I can to make certain that the Coalition wins the next election and that Bill Shorten never ever becomes Prime Minister."

And it was a departure from his usual grim outlook as home affairs minister as he shook his fist at people smugglers and asylum seeker supporters. Not today.

Mr Dutton ran through his CV to underline his capacity for the prime ministership, throwing in a John Howard reference to boost his conservative credentials.

Earlier, Mr Turnbull mounted a counter argument and reminded fellow Liberals that voters would not be impressed by leadership shenanigans.

He issued "a reminder for parties and governments to be united and determined to keep delivering for the people for whom they work - 25 million Australians".

Mr Turnbull told reporters: "We know that instability undermines the ability of any government to get anything done.

"Unity is critical. We cannot allow, as I said in the party room today, our internal issues to undermine our work, to create a risk, a real risk, that Bill Shorten will be the prime minister."

Mr Dutton's entry to the leadership beauty contest was needed because while he was a high-profile minister, many voters know little about him, or simply liked or disliked him for his stop-the-boats management.

Dutton yucks it up on the backbench. Picture: AAP Image/Mick Tsikas

"I have been on the frontbench for 14 years and have served four Liberal leaders loyally including Malcolm Turnbull," Mr Dutton said.

"Over that period of time I have been assistant treasurer to Peter Costello and John Howard, with whom I work quite closely and to this day I consider a mentor.

"I have been the shadow minister for health and finance, I have been the health minister, the minister for sport and I have been the minister for workforce participation.

"But I have most enjoy being minister for home affairs because of the people who work within those agencies and the incredibly important work that they support."

Some of the boasts on his leadership shingle will be challenged.

"I am proud of the fact that I got children out of detention. We have now moved almost 400 people off Manus Island and Nauru and that is a significant achievement," he said.

And some will seem strange: "I worked closely with Malcolm Turnbull to make sure we can achieve that."